Impact wrench



J. P. NEWMAN Nov. 27, 1951 IMPACT WRENCH 2 SHEETSh-SHEET l Filed July19, 1948 NIIIIIIIH I wv E .M M NE n 1N p. M l W. JY B Nm., 27, 1%?1 J.P. NEWMAN A21,576,85

IMPACT WRENCH Filed July 19, 1948 2 SHEETS--SHEET 2 /WTUQNES/S PatentedNov. 27, V1951 UNITED srrgg am@ ofFFICE This invention relates to a newand improved form of impact Wrench.

A particular object ci the invention is to provide a power driven impactwrench having means :for adjustment of the magnitude oi the blows orimpacts delivered by the wrench.

Another object is to provide improved vstructure for alternatelyconnecting and disconnecting the driven member from the power drivendrive shaft.

Another object isto provide an impact Wrench having working parts which'are capable of 'economical manufacture in quantity and which may bereadily disassembled for inspection, repair or replacement.

Further and morev detailed objects and advantages will appearherelnafter.

In the drawings:

Figure 1 is a side elevation partly in section showing a preferredembodiment of 'my invention.

Figure 2 is a front'elevation thereof.

ligure 3 is an axial sectional view vpartly broken away of that portionof the device indicated by the circle' 3--3`in Figure 1.

Figure 4 is a sectional view of a modified form of the deviceillustrated in Figure 3.

Figure 5 is a sectional elevation taken' substantially on the lines54-5-as shown' in FigureS.

Figure 6 is a sectional view taken substantially on the lines 5-'-6 asshown in Figure'fl.

Figure 7 is an end View oi the adjusting wedge used in connection withmyinvention.

Figure 8 is a side elevation of the*v adjusting wedge.v

Figure 9 is a side elevation of the cam member utilized inconnectionwith that form-oi my invention shown in Figures 1 and 3.

Figure 10 is a rear elevation'thereof.

Figure 11 is a front elevation of the cam member.

Figure 12 kis a side elevation partly brokenv away of the driver memberemployed in that form oi' my invention shown in Figures 1 and 3.

Figure 13 is a front end elevation thereof.

Referringto the drawings, the impact Wrenchv embodying my invention maybe provided with an electric motor I0 suitably mounted within a housingll. A downwardly extending handle portion l2 on the housing Il isproportioned to be received Within the palm of the hand of the user, anda trigger element I3 pivotally mounted on the handle portion is adaptedto operate a control switch (not shown) for regulating the operation ofthe electric motor I0. Electrical current rfor the `vmotor `may beysupplied through 7 Claims. (Cl. lim-30.5)

extends into the bearing sleeve 28.

the cable M. Aswitch leverlllmay` also be mountedon `the handle l2 forreversing the di# rection or the motor Viii-when desirech It isIrecognized that an -air driven motcrniay-besub'- stituted for thevelectric motor if desired.,` since the type of' powermeans employed forturning the drive shaft doesnot constitute an important part ofmy'invention;

Reduction gearingmay be provided fordriving the drive' shaft'lt from themotor shaft il, and as shown in the drawings this gear-ing may includethe small pinion gear lon theA motor shaft driving the larger gearllonthel countershait 2Q. A pinion 2l also xed on the countershaft itengages the largerfdriven'gear 22 which is fixed to the drive-shaft lliby any convenient means suchy as, for-example, the'key 23. The housing Hprovides suitable bearingsA for the motor shaft li and lfor-thevrearward-end of the drive shaft I6.-

A cylindrical housing extensionV orfshellis telescopcally received.Vover -the forwardl projec' tion 25 ofthe housing ll and is releasablycon-` nected'thereto by means oi-the spring urged de# tent-.26 which isreceived inalateral opening 2l in the shell 2li. The'forward projectingend of the shell 2t is' connected byany suitable means to the bearingsleeve 28.- Afdrive shaft i'extends axially through the shell 2li andYits outer rend-23 A* resilient drive sleeve it encircles the driveshaftlt-for a portion of its length and is connected :at its rearwardy end invdriving relationship with the drive shaft it by means offthefpinconnection 3l. by pins 32 to the hammer member 33 which is` rotatablymounted within the shell 2te The sleeve member'llispreferablyconstructed ofrubber or oi rubberlike material so that the-forward endoiV the sleeve and the hammer member 33 may be'drivenby the `shaft l butbe capable of relative angular movement with respect thereto.

shuttle or locking dog may move radially withil respect to the shaft16.1` Acompres'si'on spring:

3l' mounted in a cavity 3B and restingon a shoul der 39 withinthelocking dog 'urges -a contact shoe4t into engagement vvith'thesh'aft*l6so"' The forwardend ofthe sleeve Sil lis connected.`

The hammer member 33 is provided with 'a- This lockingdog` is-v that thelocking dog 35 is normally biased to move in a radial direction. Thelocking dog 35 is pro vided on its forward side with a cylindrical bore4I. The cylindrical portion 42 of the cam member 43 is positionedeccentrically with respect to the bore 44 which receives the forward endof the drive shaft I6. This eccentric 42 is received within the bore 4Iin the locking dog 35.

The external cylindrical surface 45 of the cam member 43 is rotatablyreceived within the cylindrical bore 45 of the driver member 41. Thedriver member 41 is in turn rotatably mounted within the bearing sleeve28. As shown clearly in Figures 12 and 13 the driver member 41 isprovided with circumferentially spaced projections 48 and 49 on whichare provided driving jaw surfaces 50, 5I, 52 and 53. The forward end ofthe driver member 41 projects from the bearing sleeve 28 and is providedwith a noncircular portion 54. This noncircular portion 54 ordinarily isformed as a square. A conventional socket member 55 is provided with asquare opening 56 for reception of the noncircular projection 54 and isalso provided with the usual socket 51 for reception of a nut or bolthead. A retaining spring 53 may be mounted in a groove on the forwardend of the driver 41 for frictional engagement with the socket member toretain the same in position.

The projecting end of the driver 41 is axially threaded as shown at 59to receive a .set screw 6I). A central protrusion 6I on the set screw 6Ucontacts the end 62 of the adjusting wedge member 63. As shown inFigures 7 and 8, this adjusting wedge has a nose portion 64 constitutinga cylindrical element cut away by a plane 65 on its lower side andhaving laterally extending ears 65 at its forward end. The ears 66 arereceived within the slot 61 formed in the forward end of the cam member43 (see Figures 9 and 10). The set screw 66 may be adjusted axially sothat the adjusting wedge member 63 has greater or less clearance alongthe plane B5 with the complementary inclined plane surface 58 formednear the forward end of the drive shaft I6. The set screw 601 can bethreaded axially to take up all clearance between the surfaces 65 and 68or it can be retracted to permit clearance to develop between theseplane surfaces. It will be noted that the adjusting screw is readilyaccessible through the threaded opening 59 for adjustment of theclearance between the surfaces 65 and 58 without disassembling the partsof the impact wrench.

In operation the drive shaft I6 is turned byY the motor II] andreduction gearing. S0 long as no resistance to rotation is imposed bythesocket member 55 the drive shaft I6, hammer member 33, locking dog 35,cam member 43 and driver 41 rotate as a unit with respect to the shell24 and bearing sleeve 28. When resistance to rotation of the socketmember 55 is encountered the driver 41 slows down relative to the driveshaft I6. The

shuttle or locking dog 35 moves radially outwardly under action of thespring 31. As soon as its end surface 69 moves angularly out ofengagement with the arcuate surface 10 defining the inner boundary ofthe lug 49 on the driver 41, the locking dog 35 is then in the positionshown in phantom lines in Figure 13. Since the driver 41 is rotatingslower than the hammer member 33 and locking dog 35, the locking dogmoves angularly relative to the driver 41 until it contacts the jaw face50 on the lug 48. This results in an impact which is transmitted to thedriver 41 and socket member 55. The hammer member 33 changes its rate ofangular rotation very rapidly,

and its rotating inertia therefore is available to produce the requiredshock or impact.

When the shuttle or locking dog 35 engages the jaw face 50 it acts as akey to connect the hammer member 33 solidly with the driver 41. Sincethe hammer member is driven by the resilient sleeve 30 it is enabled toslow down or stop momentarily while the rotation of the drive shaft I6continues, the relative rotation being absorbed by the resilience of therubber-like sleeve 30. Continued rotation of the drive shaft I6 acts toturn the cam member 43 relative to the locking dog 35, and the eccentric42 then engages the cylindrical surface 4I within the locking dog toretract it toward the axis of the drive shaft I6. As soon as the lockingdog is retracted toward a central position it ceases to engage the jawface 50 and takes its position with its outer end 69 in engagement withthe arcuate surface 1I within the lug 48. Resistance to rotation imposedby the socket member 55 will continue to cause relative turning motionbetween the driver 41 and the drive shaft I6 with the result that thespring 31 will shift the locking dog 35 within its groove 34 in thehammer member 33 and cause it to strike a blow against the jaw face 53on the lug 49. If the socket member 55 is engaged in tightening a nut ona bolt the effect is to apply two separate impacts per revolution of thedrive shaft I6. When the nut reaches its final tightened position thesocket member 55 and driver 41 cease to rotate at all with the resultthat the hammer member 33 comes to a stop and accelerates rapidly twiceduring each revolution of the drive shaft I6. If it is desired to removea tightened nut from a bolt, or if it is desired to tighten a nut havingleft-hand threads, the direction of the motor I0 is reversed by means ofthe switch I5 and in such cases the jaw faces 52 and 5I on the driver 41become operative. The action of the shuttle or locking dog 35 and cammember 43 is substantially the same, however.

The magnitude of the individual impacts transmitted to the driver 41 maybe varied by adjusting the screw 60. This serves to adjust the amount ofclearance provided between the surface 65 on the wedge member 63 and thesurface 68 on the end of the drive shaft I5. In effect this produces alost motion connection between the drive shaft I6 and the cam member 43.and this in turn changes the extent of relative angular movementpermitted between the drive shaft I6 and the hammer member 33. Therubber-like sleeve 35 is therefore wound up to a greater angular extentwhen the wedge member 68 is retracted than when it is advanced. Therearward end of the rubber-like sleeve member 30 turns at a uniformangular rate with the drive shaft I6 since it is connected to it bydrive pin 3l. The forward end, however, which is connected to the hammermember 33 turns nonuniformly and the extent of angular movement withrespect to the shaft depends on the point in the operating cycle atwhich the cam 43 moves the locking dog 35 to release the drivingconnection between the hammer member 33 and the driver member 41. Thus,by turning the set screw to increase the clearance between the surfaces65 and 58, a heavier impact is transmitted to the driver 41. Converselyadjustment of the screw 6D in a direction to reduce the amount ofclearance between the surfaces 65 and 68 reduces the magnitude of theindividual impacts. This is a highly desirable feature since it enablesthe imamai 5x pact wrench assembly to be used over ak wide range ofsizes of bolts and nuts..

Should it be necessary or desirable to inspect the operating parts ofthe impact wrench assembly, the spring urged detent 26 is manuallydepressed to permit the shell 24 and associated parts contained thereinto be moved axially away from the motor and gear housing I I.' The drivepin 3| remains in the drive shaft I0 and the sleeve 30 with its drivingslots 30a for the pin 3| remains with the shell 24.

In the modied form of my invention shown in Figures 4 and 6, theradially movable shuttle 35 is replaced by an axially movable clutchingdog |00. This clutching dog is mounted in a radial slot |0| formed inthe end face of the hammer member 33a. The cam member 43 is replaced bythe cam member |02 and the driver member 41a is provided with jaw faces|04. A coil spring encircles a portion of the drive shaft Mia. Thisspring engages the central boss portion |00 of the clutching dog |00 atone end and engages a collar |01 at the other end. The collar |01 isfixed on the shaft I 6a. The resilient sleeve 30a may be substantiallyidentical to the sleeve 30 described in connection with the otherfigures. The shell 24a and bearing sleeve 28a. likewise may be identicalto those previously described.

The cam member |02 is rotatably mounted within the driver member 41a andreceives the adjusting wedge 03a in a manner similar to that previouslydescribed. The rearward end face |08 of the cam member |02 comprises aplane radial surface which is interrupted for a portion of its peripheryby a raised eminence or cam nose |09. This raised eminence issymmetrical in that it slopes equally on both sides to a central highpoint. A counterbore I I0 is provided in the cam member |02 to receivethe forward end of the boss |03 of the clutching dog when the dog is inits forward operative position. A rounded surface 1||| is provided onthe clutching dog which is adapted to ride on the cam surface |09 and onthe radial surface |08. Relative angular movement between the hammermember 33a and the cam member |02 causes the clutching dog |00 to moveaxially along the drive shaft I6a. The clutching dog |00 is moved to theleft as shown in Figure 4 under action of the compression spring |05 andis moved to the right by the engagement of the cam surface |09 with thefollower surface I. In operation the drive shaft I0a, sleeve 30a, hammermember 33a, cam member |02 and driver 41a rotate as a unit so long as noresistance to rotation is imposed upon the noncircular projection 54a.When such resistance is encountered the driver 41a slows down or stops.The clutching dog |00 is carried around with the hammer member 33a andthe follower returns down the slope of the cam surface |09 and onto theradial surface |08. This brings the radially extending ear I I2 of theclutching dog |00 into engagement with one of the jaw faces |04. Animpact results on the driver 41a. The hammer member 33a is then solidlyconnected with the driver ila through the sides of the slot |0I,clutching dog |00 and jaw face |04. The hammer member 33a remains atrest or rotates at a slower speed than the shaft Ia while the cam member|02 rotates to bring the raised eminence or nose |09 into contact withthe follower portion |I I and thus move the clutching dog back into thebottom of the slot I0| and out of engagement with the jaw face |04. Theend 'of the drive shaft' 16a is slanted' on an inclined plane surface68a for engagement with the corresponding plane surface 65a on theadjusting wedge 63a. Movement of the adjusting screw 60a has the eff-ectof varying the magnitude of the individual impacts delivered to thedriver 41 in the same lmanner as described above.

Having fully described my invention, it is to be understood that I donot wish to be limited to the details herein set forth, but my inventionis of the full scope of the appended claims.

I claim:

i. In an impact wrench, the combination of a drive shaft; a drivermember mounted co--l axially of the drive shaft; power means forrotating the drive shaft; a hammer lmember rotatably mounted coaxiallyof the drive shaft; a resilient driving member adapted to rotate thehammer member and driven from the drive shaft; a movabie ciu-tch elementslidably lmounted with respect to the hammer member and constrained torotate therewith; the drive member being provided-with a jaw face; a cammember; means including relatively adjustable elements forming anangular lost motion connection whereby the cam member may be driven fromthe drive shaft; resilient means acting to move the clutch element intoengagement with the jaw face; and cooperating parts on the cam memberand clutch element for moving the latter in a direction in opposition tosaid resilient means.

2; In an impact wrench, the combination of a drive shaft; a drivermember mounted coaxially of the drive shaft; power` means for rotatingthe drive shaft; a hammer member rotatably mounted coaxially of thedrive shaft; a rubberlike sleeve member adapted to rotate the hammermember and driven from the drive shaft; a mowy able clutch elementslidably mounted with respect to the hammer member and constrained torotate therewith; the driver `member being provided witha jaw face; acam member; meansv including relatively adjustable elements forming anangular lost motion connection whereby the cam member may be driven fromthe drive shaft; resilient means acting to move the clutch element intoengagement with the jaw face; and cooperating parts on the cam memberand clutch element for moving the latter in a direction'in opposition tosaid resilient means.

3. In an impact wrench, the combination of: a drive shaft; a drivermember mounted coaxially of the drive shaft and provided with anoncircular projecting end; a hammer member rotatably mounted coaxiallyof the drive shaft; a resilient driving member adapted to rotate thehammer member and driven from the drive shaft; a movable clutch elementslidably mounted with respect to the hammer member and constrained torotate therewith; the driver member being provided with a jaw face, acam member; means including relatively adjustable elements forming anangular lost motion connection whereby the cam member may be driven fromthe drive shaft, one of said elements being accessible through theprojecting end of the driver member; resilient means acting to move theclutch element into engagement with the jaw face; and means on the cammember for moving the clutch element in a direction in opposition tosaid resilient means.

4. In an impact wrench, the combination of z a drive shaft; a drivermember mounted coaxially of the drive shaft and provided with anonatraen circular projecting end; a hammer member rotatably mountedcoaxially of the drive shaft and provided with a radial slot; aresilient driving member adapted to rotate the hammer member and drivenfrom the drive shaft; a movable clutch element slidably mounted in thehammer member slot; the driver member being provided with a jaw face; acam member; means including relatively adjustable elements forming anangular lost motion connection whereby the cam member may be driven fromthe drive shaft, one of said elements being accessible through theprojecting end of the driver member; resilient means acting to move theclutch element into engagement With the jaw face; and means on the cammember for moving the clutch element in a direction in opposition tosaid resilient means.

5. In an impact Wrench, the combination of: a drive shaft having a planesurface inclined with respect to the shaft axis; a driver member mountedcoaxially of the drive shaft and provided with a noncircular projectingend; a hammer member rotatably mounted coaxially of the drive shaft; aresilient driving member adapted to rotate the hammer member and drivenfrom the drive shaft; a movable clutch element slidably mounted withrespect to the hammer member and constrained to rotate therewith; thedriver member being provided with a jaw face; a cam member; meansincluding an adjustable wedge element adapted to cooperate with the saidplane end surface on the shaft to form an angular lost motion connectionwhereby the cam member may be driven from the drive shaft; resilientmeans acting to move the clutch element into engagement with the jawface; and means on the cam member for moving the clutch element in adirection in opposition to said resilient means.

6. In an impact wrench, the combination of a power driven shaft; adriver member and a hammer member each rotatably mounted coaxially ofthe shaft; a resilientdriving member encircling the shaft and adapted torotate the hammer member upon rotation of the shaft; a radially movableclutch element slidably mounted with respect to the hammer member andconstrained to rotate therewith; the driver member being provided with ajaw face; a cam member; means whereby the cam member may be driven fromthe drive shaft; resiilent means acting to move the clutch elementradially into engagement with the jaw face; and cooperating parts on thecam member and clutch element for moving the latter away from the facein opposition to said resilient means.

7. In an impact wrench, the combination of: a drive shaft; a drivermember mounted coaXially of the drive shaft; power means for rotatingthe drive shaft; a hammer member rotatably mounted coaxially of thedrive shaft; a rubber-like sleeve adapted to rotate the hammer memberand driven from the drive shaft; a radially movable clutch elementslidably mounted with respect to the hammer member and constrained torotate therewith; the driver member being provided with a jaw face; acam member; means whereby the cam member may be driven from the driveshaft; a spring carried on the clutch member and acting against thedrive shaft to move the clutch element radially outwardly intoengagement with the jaw face; and an eccentric on the cam member formoving the clutch element radially inwardly in opposition to saidspring.

JOHN P. NEWMAN.

REFERENCES CITED The following references are of record in the iile ofthis patent:

UNITED STATES PATENTS Number Name Date 2,061,843 Meunier Nov, 24, 19362,158,303 Pott May 16, 1939

